ZOAHARIAN.COM – The threat of a Megathrust earthquake in the southern region of Java Island is once again a concern. If the enormous energy locked in the subduction zone south of Java is released at once, an earthquake measuring up to Magnitude 8.7 could potentially occur and trigger a tsunami with a height of up to 20 meters.

The impact not only threatens the southern coastal area of ​​West Java, but can also spread to Banten, Lampung, and even the northern coast of Jakarta.

Indonesia itself is in the Pacific Ring of Fire area which has high tectonic activity. There are 14 Megathrust segments that are of concern because they have the potential for large earthquakes.

One area that needs to be watched out for is the South Java Megathrust segment which stretches to the Sunda Strait. Apart from that, there is a Sumatra segment whose impact can also reach the Sunda Strait region or known as the Enggano Segment.

Researcher at the BRIN Geological Disaster Research Center, Nuraini Rahma Hanifa, explained that the energy locked in the subduction zone south of Java continues to increase over time.

According to him, this accumulated energy could one day reach the point of release through sudden movements of the earth's plates. This event can trigger an earthquake with very strong shaking.

If the accumulated energy is released all at once, the strength of the earthquake is estimated to reach a magnitude of 8.7.

This large shock has the potential to shift the sea water column and produce tsunami waves that spread in various directions until they reach land.

"All the coasts of Banten will be affected but with different (tsunami) heights," said Rahma when talking to CNBC Indonesia some time ago, quoted on Sunday (8/11/2026).

Pangandaran Tsunami Could Reach 20 Meters

Rahma explained that if the Megathrust in the southern segment of Java, especially the Pangandaran area, experiences a release of energy, the tsunami that is formed is estimated to reach a height of around 20 meters.

The wave could then spread to the Sunda Strait area and hit a number of coastal areas in Banten and Lampung.

For the Banten coastal area, the tsunami height is estimated to be in the range of 4 to 8 meters.

"The Banten coastal area experienced a tsunami of approximately 4 to 6 or 8 meters," he said.

Meanwhile, the Lampung area which faces directly to the Sunda Strait is also potentially affected by tsunami waves.

"Lampung, which faces the Sunda Strait, will all be hit," he added.

Jakarta Could Be Hit by a Tsunami in 2.5 Hours

The threat of the South Java Megathrust also has the potential to reach the Jakarta area.

Based on Rahma's calculations, the tsunami is estimated to reach the northern coastal area of ​​Jakarta with a height of around 1 to 1.8 meters.

The arrival time of the tsunami wave is estimated to be around 2.5 hours after the earthquake occurred.

However, this impact is estimated to be concentrated in the northern coastal area of ​​Jakarta, not the entire capital area.

"It took 2.5 hours for the tsunami to arrive. If the southern part of Java arrived in 40 minutes, Lebak took 18 minutes. OK, the first to be affected was the North Jakarta area," he explained.

This time estimate shows that areas closer to the earthquake source have a much shorter response time.

BRIN Reminds the Public to Remain Alert

BRIN reminded the public to increase preparedness to face the potential Megathrust earthquake disaster.

The impact of a large earthquake is not only in the form of ground shaking and tsunamis. These disasters can also trigger various further impacts, ranging from deaths, injuries, infrastructure damage, to environmental damage.

Apart from that, people's social and economic activities have the potential to be disrupted. Basic services such as electricity, clean water, transportation, communications and health facilities can also experience disruption.

Meski potensi Megathrust perlu diwaspadai, penting dipahami bahwa perkiraan kekuatan gempa dan tinggi tsunami merupakan skenario pemodelan, bukan kepastian bahwa bencana akan terjadi dalam waktu dekat.

People, especially those living in coastal areas, are advised to understand evacuation routes, recognize the natural signs of a tsunami, and immediately move away from the coast and towards higher ground if a strong earthquake occurs or a tsunami warning is issued.

Early preparedness is an important step to reduce the risk of loss of life when a disaster occurs.